Problem: $\dfrac{9}{2} \div \dfrac{2}{5} = {?}$
Dividing by a fraction is the same as multiplying by the reciprocal of the fraction. The reciprocal of $\dfrac{2}{5}$ is $\dfrac{5}{2}$ Therefore: $ \dfrac{9}{2} \div \dfrac{2}{5} = \dfrac{9}{2} \times \dfrac{5}{2} $ $ \phantom{\dfrac{9}{2} \times \dfrac{5}{2}} = \dfrac{9 \times 5}{2 \times 2} $ $ \phantom{\dfrac{9}{2} \times \dfrac{5}{2}} = \dfrac{45}{4} $